Onset of rosette formation during spontaneous neural differentiation of hESC and hiPSC colonies

In vitro neural differentiation of human embryonic stem cells (hESCs) is an advantageous system for studying early neural development. The process of early neural differentiation in hESCs begins by initiation of primitive neuroectoderm, which is manifested by rosette formation, with consecutive differentiation into neural progenitors and early glial-like cells. In this study, we examined the involvement of early neural markers – OTX2, PAX6, Sox1, Nestin, NR2F1, NR2F2, and IRX2 – in the onset of rosette formation, during spontaneous neural differentiation of hESC and human induced pluripotent stem cell (hiPSC) colonies. This is in contrast to the conventional way of studying rosette formation, which involves induction of neuronal differentiation and the utilization of embryoid bodies. Here we show that OTX2 is highly expressed at the onset of rosette formation, when rosettes comprise no more than 3–5 cells, and that its expression precedes that of established markers of early neuronal differentiation. Importantly, the rise of OTX2 expression in these cells coincides with the down-regulation of the pluripotency marker OCT4. Lastly, we show that cells derived from rosettes that emerge during spontaneous differentiation of hESCs or hiPSCs are capable of differentiating into dopaminergic neurons in vitro, and into mature-appearing pyramidal and serotonergic neurons weeks after being injected into the motor cortex of NOD-SCID mice.     

Mechanism of action of the tri-hybrid antimicrobial peptide LHP7 from lactoferricin,HP and plectasin on Staphylococcus aureus

The tri-hybrid peptide-LHP7 has the potent activity against Gram-positive and Gram-negative as well as fungi, but its mechanism of action has remained elusive. The effluences of LHP7 on the Staphylococcus aureus cell membrane and targets of intracellular action were investigated. LHP7 exhibited an inhibitory effect on the S. aureus growth, similar to those achieved by plectasin, vancomycin and gramicidin. The membrane integrity studies confirmed that LHP7 disrupted the cell membrane, indicating a membrane permeabilizing killing action. A marginal decline in the intensity fluorescence indicated no significant depolarization of the membrane potential following LHP7 treatment. Furthermore, electron microscopy showed that cell shrinkage, cell wall thickening, cellular content leakage, and cell disruption were observed in the cells treated with LHP7. A gel retardation assay showed that LHP7 bound to the genomic DNA of S. aureus or plasmid DNA at a mass ratio of 2.5–10 (peptide/DNA). Circular dichroism indicated that LHP7 inserted into the groove of DNA. The cell cycle analysis showed that after the treatment with LHP7 for 30 and 60 min, the proportion of cells in I-phase increased from 8.71 to 12.09 % and from 8.71 to 15.68 %, indicating that LHP7 induced arrest of cells in the I-phase. These results would conduce to elucidate its underlying antibacterial mechanism.     

多巴胺与神经退行性疾病研究进展

多巴胺调控人类的情绪和认识能力,包括思想、感觉、理解、推理等,同时,它也在人类的运动功能中发挥重要作用。研究表明多巴胺的合成、储存、释放、降解和重摄取等失衡均与中枢神经系统的多种退行性疾病有密切联系,同时许多治疗疾病的有效药物也围绕多巴胺的研究而产生,如多巴胺替代疗法改善帕金森病的运动症状,多巴胺受体阻断剂可改善舞蹈病的运动症状以及调节多种疾病的精神症状,在临床上都取得了可喜的疗效。然而目前未发现与多巴胺代谢直接相关的基因突变,因此未来需要继续深入研究在神经退行性疾病中造成多巴胺代谢失常的机制,旨在为临床新药物靶点和新治疗手段的研发提供线索。     

温度对鳙幼鱼疲劳引起的生理变化和游泳能力的影响研究(英文)

鳙(花鲢)在自然环境中分布于中国南部流域至阿穆尔河,是重要的经济性鱼类,具江湖生殖洄游特性。大坝建设阻碍了其洄游产卵繁殖通道,导致自然环境中其繁殖力的下降,需要有效的过鱼设施帮助鳙通过大坝等水流屏障。为了设计高效的鱼道引导鳙通过,本文通过自制密封的鱼类游泳实验装置,研究了鳙幼鱼游泳能力。测定了5个温度(5、10、15、20和25℃)下鳙幼鱼的临界游泳速度。通过测定不同温度下,疲劳前后血清总蛋白(TP)、血糖(GLU)和甘油三酯(TG)含量,评价疲劳运动引起的生理胁迫。结果表明,在试验温度范围内,随着温度的升高,临界游泳速度显著提高(P0.05)。25℃时临界游泳速度最大,为7.01 BL/s(1.19 m/s)。在疲劳运动后,血清总蛋白、血糖和甘油三酯含量显著升高(P0.05)。水温低于15℃与高于15℃相比,鳙疲劳运动后血清总蛋白、血糖和甘油三酯含量显著升高。以鳙幼鱼为研究对象,研究了非适宜温度环境和疲劳运动胁迫下鱼类的生理反应。以期为鱼类生理学研究和渔业保护管理等领域提供理论依据,为制定有效的鱼道提供数据参考。     

小麦旗叶长、宽及面积的QTL分析

以小麦品种‘小偃81’和‘西农1376’构建的含236个家系的自交重组系(RIL)群体(F2:7、F2:8代)为研究材料,采用完全随机区组设计,连续2年在陕西杨陵、河南驻马店和山东济南于灌浆期(花后20d)随机取每个株系10株测量旗叶长、宽,并利用172个SSR标记构建了遗传连锁图谱,通过基于完备区间作图法的QTL IciMapping V3.2软件,对控制小麦旗叶长、宽和面积的数量性状位点(QTL)进行了加性效应分析。结果发现:(1)9个旗叶长QTLs位于1A、4A、3B、5D和7D染色体上,单个QTL可解释5.10%~16.44%的表型变异;10个旗叶宽QTLs位于1A、3A、5A、7A、3B和5D染色体上,单个QTL可解释4.63%~14.24%的表型变异;12个旗叶面积QTLs位于1A、4A、3B、2D和5D染色体上,单个QTL可解释4.25%~22.67%的表型变异。(2)控制小麦旗叶长、宽和面积的QTLs存在差异,同一QTL在不同性状中的遗传贡献率也不同。(3)同一性状在同一年份,不同地点和在不同年份,相同地点下检测到的QTLs有的相同,但有的差异明显。(4)有些控制不同性状的QTLs在染色体的同一标记区间,表现一因多效。研究表明:位于1A和5D染色体上的2个加性QTLs都同时控制旗叶长、宽和面积,且前者为主效基因,后者遗传贡献率也较大,可用于标记辅助育种和分子聚合育种。     

Comparative Genomic Analysis of N2-Fixing and Non-N2-Fixing Paenibacillus spp.: Organization,Evolution and Expression of the Nitrogen Fixation Genes

We provide here a comparative genome analysis of 31 strains within the genus Paenibacillus including 11 new genomic sequences of N₂-fixing strains. The heterogeneity of the 31 genomes (15 N₂-fixing and 16 non-N₂-fixing Paenibacillus strains) was reflected in the large size of the shell genome, which makes up approximately 65.2% of the genes in pan genome. Large numbers of transposable elements might be related to the heterogeneity. We discovered that a minimal and compact nif cluster comprising nine genes nifB, nifH, nifD, nifK, nifE, nifN, nifX, hesA and nifV encoding Mo-nitrogenase is conserved in the 15 N₂-fixing strains. The nif cluster is under control of a σ⁷⁰-depedent promoter and possesses a GlnR/TnrA-binding site in the promoter. Suf system encoding [Fe–S] cluster is highly conserved in N₂-fixing and non-N₂-fixing strains. Furthermore, we demonstrate that the nif cluster enabled Escherichia coli JM109 to fix nitrogen. Phylogeny of the concatenated NifHDK sequences indicates that Paenibacillus and Frankia are sister groups. Phylogeny of the concatenated 275 single-copy core genes suggests that the ancestral Paenibacillus did not fix nitrogen. The N₂-fixing Paenibacillus strains were generated by acquiring the nif cluster via horizontal gene transfer (HGT) from a source related to Frankia. During the history of evolution, the nif cluster was lost, producing some non-N₂-fixing strains, and vnf encoding V-nitrogenase or anf encoding Fe-nitrogenase was acquired, causing further diversification of some strains. In addition, some N₂-fixing strains have additional nif and nif-like genes which may result from gene duplications. The evolution of nitrogen fixation in Paenibacillus involves a mix of gain, loss, HGT and duplication of nif/anf/vnf genes. This study not only reveals the organization and distribution of nitrogen fixation genes in Paenibacillus, but also provides insight into the complex evolutionary history of nitrogen fixation.     

SELDI-TOF-MS筛选慢性阻塞性肺疾病血清标志蛋白的初步研究

目的:利用表面增强激光解吸电离飞行时间质谱技术(SELDI-TOF-MS)筛选慢性阻塞性肺疾病(COPD)血清特异标志物。方法:应用SELDI-TOF-MS技术检测30例COPD稳定期患者和30例健康对照者血清蛋白指纹图谱,采用Biomarker pattern软件进行分析,建立COPD的诊断模型。结果:COPD患者血清蛋白图谱与对照组相比,在相对分子质量2000-15 000范围内共检测到75个蛋白峰,发现19个有统计学差异的蛋白峰(P0.05)。通过对COPD组与对照组间的数据作进一步分析,经BPS软件分析,建立质荷比(M/Z)3 167、4 645的差异蛋白组成的诊断模型,其诊断敏感度为96.67%,特异度为96.67%。结论:SELDI-TOF-MS技术是一种快速、简单易行、用量少和高通量的分析方法。能直接筛选出COPD血清中特异表达标志物,用特异表达标志物建立的诊断模型能有效区分COPD患者与健康对照者,有望成为COPD诊断的辅助指标。     

Investigating design principles of micropatterned encapsulation systems containing high-density microtissue arrays

Immunoisolation is an important strategy to protect transplanted cells from rejection by the host immune system.Recently,microfabrication techniques have been used to create hydrogel membranes to encapsulate microtissue in an arrayed organization.The method illustrates a new macroencapsulation paradigm that may allow transplantation of a large number of cells with microscale spatial control,while maintaining an encapsulation device that is easily maneuverable and remaining integrated following transplantation.This study aims to investigate the design principles that relate to the translational application of micropatterned encapsulation membranes,namely,the control over the transplantation density/quantity of arrayed microtissues and the fidelity of pre-formed microtissues to micropatterns.Agarose hydrogel membranes with microwell patterns were used as a model encapsulation system to exemplify these principles.Our results show that high-density micropatterns can be generated in hydrogel membranes,which can potentially maximize the percentage volume of cellular content and thereby the transplantation efficiency of the encapsulation device.Direct seeding of microtissues demonstrates that microwell structures can efficiently position and organize pre-formed microtissues,suggesting the capability of micropatterned devices for manipulation of cellular transplants at multicellular or tissue levels.Detailed theoretical analysis was performed to provide insights into the relationship between micropatterns and the transplantation capacity of membrane-based encapsulation.Our study lays the ground for developing new macroencapsulation systems with microscale cellular/tissue patterns for regenerative transplantation.